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In a SQL database query, a correlated subquery (also known as a synchronized subquery) is a subquery (a query nested inside another query) that uses values from the outer query. This can have major impact on performance because the correlated subquery might get recomputed every time for each row of the outer query is processed.
Queries can be nested so that the results of one query can be used in another query via a relational operator or aggregation function. A nested query is also known as a subquery. While joins and other table operations provide computationally superior (i.e. faster) alternatives in many cases, the use of subqueries introduces a hierarchy in ...
A hierarchical query is a type of SQL query that handles hierarchical model data. They are special cases of more general recursive fixpoint queries, which compute transitive closures . In standard SQL:1999 hierarchical queries are implemented by way of recursive common table expressions (CTEs).
MS SQL Server (This also works on Microsoft SQL Server 6.5 while the Select top 10 * from T does not) SELECT * FROM T LIMIT 10 OFFSET 20 Netezza , MySQL , MariaDB (also supports the standard version, since version 10.6), SAP SQL Anywhere , PostgreSQL (also supports the standard, since version 8.4), SQLite , HSQLDB , H2 , Vertica , Polyhedra ...
The nested set model is a technique for representing nested set collections (also known as trees or hierarchies) in relational databases. It is based on Nested Intervals, that "are immune to hierarchy reorganization problem, and allow answering ancestor path hierarchical queries algorithmically — without accessing the stored hierarchy relation".
In relational databases, a nested table is a table that is embedded within another table. Individual elements can be inserted, updated, and deleted in a nested table. Since individual elements can be modified in a nested table, they are more flexible than an array because elements in an array can only be modified as a whole, not individually. A ...
WebScaleSQL – software branch of MySQL 5.6 jointly developed by Facebook, Google, LinkedIn and Twitter to provide a centralized development structure for extending MySQL with new features specific to large-scale deployments, such as building large replicated databases running on server farms. The project's objective is to tightly follow new ...
It was developed by MySQL AB and later by Sun Microsystems and released under the GPL. Development on the GUI Tools bundle has stopped, and is now [when?] only preserved under the Download Archives of the MySQL site. [9] The GUI Tools bundle has been superseded by MySQL Workbench, and reached its End-of-Life with the beta releases of MySQL ...